The need for a significantly protective helmet of reduced bulk and very thin silhouette has existed for many years in several athletic or entertainment sports, and in some cases, military applications. The purposes creating this need and which such a helmet should provide are minimal weight with corresponding stability and maximum maneuverability or very low aerodynamic resistance depending on the helmets' intended use. Protection of the wearers' head from impacts however, remains a priority over this need. The prior art consistently demonstrates this priority being provided for by the use of substantially unitary rigid outer shells. These shells, normally lined with a variety of impact absorbing materials, must be constructed large enough to accommodate additional padding structures or lining assemblys primarily for the purpose of responding to the shape, and to a limited degree, the size of the wearers' head. The use Of such padding therefore, increases the overall bulk and corresponding weight of the helmet, adversely affecting its dimensional profiles, stability, and aerodynamic resistance.
The conflict between the priority of providing adequate protection of the wearers' head and the need for a helmet of very low aerodynamic resistance has been approached by the prior art only indirectly on a very limited basis. Attempts to provide a solution to this problem have incorporated the use of flexible or elastic fabric. Typical of this approach for example, is that shown in U.S. Pat. Nos. 3,784,984 (1974) to Aileo and 4,023,209 (1977) to Frieder, Jr. et al. In these patents a helmet liner is constructed of fabric mesh formed into pockets into which a series of energy absorbent pads are inserted. The use of elastic mesh in these helmets is intended to provide some degree of flexible response to the wearers' head shape and size. This ability however, is severely limited by the copious use of non-elastic reinforcing tapes at the margins of various panels restricting the elastic function of those panels. This contradiction appears in the above patents.
The most significant problem inherent in the prior art however, as exemplified in part by the aforementioned patents, is vulnerability to impacts at locations where various padding structures are approximately adjacent with intentional spacing. The problem also occurs at the margins and regions of integral earcup assemblys utilized for sound attenuation and communications in military applications. This weakness also occurs in a similar manner at indentations in a single unitary pad as shown in U.S. Pat. No. 4,843,642 (1989) to Brower. An increased degree of abutment of sections is claimed to occur at these indentations upon a radial impact to adjacent sections. Although the helmet dispenses with the use of an overlying outer shell, no feature is present to protect the wearers' head from impacts directly at the point of these indentations.
Recognizing these vulnerabilitys, the prior art teaches that provision for full impact protection must revert to the concept of the use of rigid substantially unitary outer shells or an assembly of parts substantially embracing this approach. Due to their inflexible nature these shells present an increased overall bulk in their silhouette with a corresponding increase in weight and diminished maneuverability. They do not present streamlined conformity to the wearers' head, but rather as objectionable encumbrances in that regard. The designs of the prior art, even with these shells installed, leave certain points and areas of the wearers' head vulnerable to direct impact and therefore do not provide complete protection. Also, in cases where these shells are removably installed as separable accessories, they may become dislodged during certain uses.
Additional drawbacks to the use of these shells include increased complexity and expense of manufacture, and inconvenience for the user who must inventory, transport, and assemble multiple components for full protection.